1. Field of the Invention
The present invention relates to the field of video surveillance, and in particular to equipment for use in applications where the need for video surveillance is temporary.
2. Description of the Related Art
As traffic in urban environs increases, the need for improvements to infrastructure also increases. This need is not always matched by available resources for road improvements; thus, a way to prioritize expenditures of resources is needed. One way to do this is to conduct traffic studies that monitor and analyze motor vehicle and pedestrian traffic at locations identified as requiring improvement.
Traffic studies may examine one or more of several components of traffic operation. For example, an intersection might be monitored for traffic density, i.e., how many vehicles pass through the intersection at any given time, and in which directions? The intersection might be monitored for compliance, i.e., how many traffic infractions occur and at what times? A cross walk might be a safety concern for school children crossing a heavily traveled street, so a study might monitor vehicle speed and density as well as pedestrian crossing at that location at critical times. Railroad grade crossings are often a concern, and a study might examine traffic patterns and behavior of motorists with respect to a grade crossing.
Any one of these studies might need to be conducted repeatedly at different times and locations in order to accurately determine where improvements or increased patrols by police are justified or will be most effective.
A common method of conducting such studies is to place one or more human observers at the particular location. There are several drawbacks to this method. First, the expense of paying observers to watch traffic, especially for extended periods, can be significant. Second, an observer may miss one event while recording another. Accuracy of recording is also an issue. For example, will an observer be able to accurately determine whether a light changed just before or just after a car enters an intersection. As the amount of data required from a single observer increases, the accuracy of the data collected will decrease. The danger also exists that an observer will falsify data, either to achieve a desired result or out of an unwillingness to persevere in the study.
While other methods and devices exist for performing such studies, these also have particular drawbacks. For example, temporary sensors placed across a road record numbers of vehicles and times of passing, but they do not record other factors, such as traffic signals or pedestrian traffic. In addition, such sensors become less effective in multi-lane roadways, and their accuracy can be compromised by multi-axel vehicles, which can be miscounted. Conventional video systems are expensive to supply and expensive to install and monitor.